M1, THE CRAB NEBULA

M1,
The Crab

On
July 4, 1054, Chinese chroniclers noted a "guest star" near the star
Zeta Tauri which "became invisible" after about a year. In 1731 John
Bevis discovered a bright nebula in the same location. Using a larger
telescope in 1844, Lord Rosse described the nebulous filaments as
resembling a crab and so it has been known as the Crab Nebula ever
since.

One
of the most studied objects in the heavens, the Crab Nebula is now
known to be the remnants of a supernova explosion. It is an expanding
gas cloud that once was the outer region of a giant star. It is
expanding at the rate of about 600 miles per second or 50 million miles
per day.

What
remains of the actual star is even more incredible. After blowing off
much of the outer shell, the remaining mass collapsed into an
incredibly tiny and dense object. So dense that atoms in the usual
sense do not exist, only neutrons. It is estimated that roughly the
mass of our Sun is compressed into an object only a few miles in
diameter. It is known as a "Neutron Star".

If
that's not enough to make it interesting, it rotates at the incredible
rate of 30 revolutions per second. That's about the same speed as the
armature in a typical electric motor. It also happens to emit a beam of
radio energy from the magnetic poles that appears to pulse at the rate
of 30 pulses per second each time it passes our point of view. This
special type of neutron star is called a "Pulsar".

The
Pulsar can be seen in the above photo as the lower right of the close
double in the center of the nebula.

The
Crab Nebula is about 6300 light years away and blazed with the light of
400 million Suns for about two weeks in 1054 AD. It is currently about
6 light years in diameter. Were it the sun, it would not only engulf
the entire Solar System but also our neighbor stars. It most assuredly
would not have been a very welcome "guest" if it were anywhere near our
Sun. We would not be here to wonder at it.

M1 Ha Light

This
image was taken using a Hydrogen Alpha filter to produce the luminence
data and the color frames from the above image for the color.

This
was a stack of 5 x 20 min exposures through the 10" telescope using the
MX716 camera.